Device for precise connection for a machine for continuous unwinding

ABSTRACT

The present invention relates to a device for precise connection for a continuous unrolling machine, comprising at least a means ( 3 ) for unrolling two spools, a strip accumulator ( 4 ) and a device for connecting ending strips ( 1 ) and new strips ( 2 ).  
     Device characterized in that the connection device is essentially constituted by adjoining an indexing station ( 5 ) for the strips ( 1  and  2 ) and by at least one means ( 6, 37 ) for precise control of the speed of movement of the strip through the joining and indexing station ( 5 ).  
     The invention is more particularly applicable to the field of machines for continuously unrolling strip material, from spools, to supply continuously printing machines, forwarding machines or the like.

DESCRIPTION

[0001] The present invention relates to the field of machines forcontinuously unrolling strip material, from spools, to supplycontinuously printing machines, forwarding machines or the like, and hasfor its object a device for precise connection for such a continuouslyunrolling machine.

[0002] The precise connection between ending and new strips of materialis necessary in certain fields, so as to ensure a perfect continuity ofdecorative or informative elements carried on said strips. Suchprecision, which consists in obtaining a high precision superposedconnection, which is to say such that the marks on an ending stripcoincide perfectly with those marked on a new strip, is particularlyimportant, for example, in the case of unrolling strips of the materialin the form of aluminum films, particularly for closing packages ofmedications or the like, which bear inscriptions disposed at regularintervals. These inscriptions thus require being perfectly offsetrelative to each other during connection of two ends of the superposedstrips, so as to guarantee perfect agreement of the inscriptions withthe contents of the package. The same problems arise in the presence ofother strips provided with markings that are to be arranged in aperfectly regular and precise manner.

[0003] At present, there is known from GB 2 148 856, an unrollingmachine using independent means for preparation of the end of the newstrip and for moving said strip so as to match a junction mark. Such anembodiment however does not permit ensuring a sufficient degree ofprecision.

[0004] There is also known, from U.S. Pat. No. 4,455,190, an unwindercomprising a device for cutting the ending strip and applying thebeginning of the new strip on the end of the cut strip provided with anadhesive, with overlap. The device according to this document does notprovide for indexing the strips, nor referencing them, nor detectingposition, nor means for moving the strips at reduced speed, it isaccordingly impossible to produce a precise superposition and to obtaina sequence of the printing between the two strips.

[0005] These known unwinding machines provide no means for moving thestrips at reduced speed under controlled tension, whereby they do notpermit producing a high precision connection, in particular because ofthe inertia of the spool and/or the various changes in strip tension,for example under the influence of motorized strip drive. However, it isvery important that the tension in the strip remain constant, and hencethat the elongation of the strip be constant, to ensure precision ofconnecting the markings.

[0006] The present invention has for its object to overcome thesedrawbacks by providing a precision connecting device for a continuousunwinding machine permitting high precision of superposed connectionbetween two strips, ending and beginning, with complete integrity of thespacing between consecutive markings.

[0007] To this end, the precision connection device for a continuousunrolling machine, comprising at least means for unrolling two spools, astrip accumulator and a connecting device, is characterized in that theconnecting device is essentially constituted by a station for joiningand indexing the strips and by at least one precise control means forthe speed of movement of the strip through the junction and indexingstation.

[0008] The invention will be better understood from the followingdescription, which relates to a preferred embodiment, given by way ofnon-limiting example and explained with reference to the accompanyingschematic drawings, in which:

[0009]FIG. 1 is a side elevational view of an unwinding machine providedwith a connection device according to the invention;

[0010]FIG. 2 is a fragmentary side elevational and cross-sectional view,on a larger scale, showing the connection device and two precise controlmeans for the speed of movement of the strip;

[0011]FIG. 3 is a fragmentary side elevational view, on a larger scale,of a station for preparing a new strip;

[0012]FIG. 4 is a fragmentary front elevational view of the strip andthe drive of the ending strip;

[0013]FIG. 5 is a schematic side elevational view showing the principleof operation of the machine;

[0014]FIGS. 6 and 7 are views on a larger scale analogous to that ofFIG. 5, showing two modes for preparation of a new strip;

[0015]FIG. 8 is a view partially in cross-section, on a large scale,showing the junction of two registering strips;

[0016]FIGS. 9a to 9 c are partial schematic views showing the operationof the strip accumulator, and

[0017]FIG. 10 is a curve of the speeds of strips during the connectionoperation.

[0018]FIGS. 1, 2 and 5 of the accompanying drawings show a continuousunrolling machine permitting continuously unrolling with superposedconnection between two strips, an ending strip 1 and a new strip 2 andcomprising at least one means 3 for unrolling two spools, a stripaccumulator 4 and a connection device.

[0019] According to the invention, the connection device is essentiallyconstituted a station for joining and indexing the strips 1 and 2 and byat least one means 6, 37 for precise control of the speed of movement ofthe strip through the joining and indexing station.

[0020] The unrolling machine according to the invention is essentiallyadapted for unwinding spools of paper, aluminum or films of othermaterial, so as to obtain a superposed high precision connection asshown in FIG. 8 of the accompanying drawings. To this end, it is amatter of obtaining a perfect coincidence between the marks 7 providedrespectively on the ending strip 1 and the new strip 2. Thus, thesections comprised between the markings 7 of the strips 1 and 2 will bejoined if it is only a matter of a single and same strip and the supplyof the machine disposed downstream will be maintained withoutinterruption and without risk of offset of the sections. The connectionof the new strip 2 to the ending strip 1 must be carried out withoutmodification of the speed of supply to the downstream machine.

[0021] This object is achieved by the use of the joining and indexingstation 5 for the strips 1 and 2 and at least one means 6, 37 forprecise control of the speed of movement of the strip through thejoining and indexing station.

[0022] According to a characteristic of the invention, the joining andindexing station 5 of the strips 1 and 2 is constituted by twosymmetrical assemblies 8 for preparation and cutting the ending strip 1and the new strip 2 and by an intermediate bearing crosspiece 9 forcutting the ending strip 1 (FIGS. 2, 4 and 5).

[0023] Each assembly 8 for preparing and cutting the ending strip 1 andthe new strip 2 is preferably constituted by a junction block 10pivotable between a preparatory position, shown at the left in FIGS. 2and 5 and in FIG. 3, and a connecting position shown at the right ofFIGS. 2 and 5 and in FIG. 4, by an indexing device 11 for the new strip2 and by a means 12 for preparatory cutting of the new strip 2. It isthus possible to position precisely the new strip 2 and to prepare itsend adapted to be joined overlappingly with the corresponding end of theending strip 1.

[0024] Each pivotable junction block 10 is, as shown more particularlyin FIGS. 2 and 3 of the accompanying drawings, in the form of a casingwhich, on the one hand, is connected to a pivoting lever 13 actuated bya jack 14 articulated by its cylinder on the body of the machine and, onthe other hand, is provided with suction means 15 and a transversebearing strip 16 for the new strip 2 during the preparatory cut and theapplication of an adhesive strip on the end, after said cut. Thus, thenew strip 2 can be perfectly maintained on the pivotable block 10 duringall the operation of preparation of its beginning and its end can be cutprecisely to receive an adhesive strip.

[0025] Moreover, each pivotable junction block 10 is provided with aknife 24 for cutting the ending strip 1, guided in a slot 25 and drivenby a jack (not shown).

[0026] Moreover, each pivotable junction block 10 is mounted on the bodyof the unrolling machine by means of a sliding bearing, not shown,actuated by a jack (not shown) for movement in direction of theintermediate bearing crosspiece 9. Such a mounting permits placing thejunction block 10 against the crosspiece 9 during cutting of the endingband 1.

[0027] The suction means 15 consists in holes provided in a surfaceadjacent to the transverse strip 16 for bearing against the new strip 2,these holes being preferably arranged in groups symmetrical relative tothe longitudinal axis of the new strip 2 and with suction chamberscontrolled pair-wise. In a known manner, each suction chamber isconnected to a central suction means by means of manual control valves.As a result, each block 10 can be adapted as a function of the width ofthe strips to be prepared.

[0028] The preparatory cutting means 12 for the new strip 2 isconstituted by a transverse support 17, mounted with the possibility ofretractable pivoting in bearings 18 and 19 of the frame of the machineand having a guide slideway 20 for a slider 21 bearing a knife 22 loadedby a spring 23. This cutting means 12 is preferably provided at the freeend of the transverse support 17, with a hook or the like, not shown,for holding it in retracted position.

[0029] The device 11 for indexing the new strip 2 is in the form of areturn roller 26 and of a gripping roller 27, adapted to exert tractionon the new strip 2, and with indexing means 28, such as a magnifyingglass or the like, mounted movably transversely to the strip 2 on asupport 29, removably fixed in a bearing 19 on the chassis of themachine. This bearing 19 can be released by pivotable retraction of thetransverse support 17 constituting the preparatory cutting means 12 forthe new strip 2.

[0030] Preferably, the body of the unrolling machine is providedrespectively at the level of each indexing device 11 for the new strip 2and in line with the bearing strip 16 of the new strip 2, in the cuttingposition of this strip 2, with bearings 18 and 19 for mounting thetransverse support 17 constituting the preparatory cutting means 12 forthe new strip 2 and for the indexing means 28.

[0031] Thus, these two elements can easily be emplaced and moved asneeded.

[0032] According to another characteristic of the invention and as shownin FIG. 3 of the accompanying drawings, the return roller 26 is mountedin a sliding bearing 30 on the body of the machine and is movable in thedirection of, or in the opposite direction of, the correspondinggripping roller 27 by means of mechanical or electrical control, such asa jack, a motor reducer assembly or the like. Another embodimentpermits, when the reference marks 7 of a new strip 2 are turned towardthe center of the spool, moving the return roller 26 relative to thegripping roller 27 by the distance necessary such that a whole number ofsections between the reference marks 7 will be located between theindexing means 28 and the position of the cut. As a result, the returnroller 26 can be adjusted into different positions relative to thegripping roller 27. Each of these positions corresponds to one format ofthe strip. These positions are referenced relative to the body of themachine, so as to facilitate preparation.

[0033] The intermediate bearing crosspiece 9 for cutting the end of thestrip 1 (FIGS. 2, 4 and 5) is preferably present in the form of an anvildisposed between the pivotable junction blocks 10 of each assembly 8 forpreparation and cutting of the ending strips 1 and new strips 2 and isprovided with two opposite transverse grooves 9′ adapted to coact withthe knife 24 of each pivotable junction block 10.

[0034] According to another characteristic of the invention, and asshown in FIG. 4 of the accompanying drawings, each assembly 8 forpreparation and cutting the ending strips 1 and new strips 2 iscompleted by a punching device 31, mounted on the body of the machineperpendicular to the anvil forming the medial bearing crosspiece 9 andcoacting with a matrix 32 provided on said anvil. This punching device31 is constituted by a punch properly so-called mounted at the end of apiston rod 33 in a guide chamber 34 and provided with means 35 forapplying the device against the anvil during the punching operation.This application means 35 of the device against the anvil is preferablyconstituted by a sleeve movable by the control jack for the punch andprovided with a resilient means 36 for compensating the finaldisplacement of the punch, in the form of a spring or the like. Thus,the punch is first moved toward the anvil and the means 35 is appliedagainst this latter, then the punching of the strip is effected duringfinal movement of the control jack.

[0035] The strip accumulator 4 is of known type and is adapted toaccumulate a reserve of strip to ensure continuous supply at constantspeed to the downstream machine, when the strips 1 and 2 are stopped forconnection. The detour rods in the accumulator 4 can move relative toeach other thanks to a jack and occupy open positions, working positionsand closed positions, as well as any other intermediate positions.

[0036] According to another characteristic of the invention and as shownin FIGS. 1, 2 and 5 of the accompanying drawings, a means 37 for theprecise control of the speed of movement of the strip through thejoining and indexing station can be constituted by a traction assembly37 for the ending strip 1, at variable speed, provided between the stripaccumulator 4 and the connection device. Such an assembly can beconstituted by a return cylinder 38, over which passes the strip 1,which is pressed against this cylinder 38 by means of a pulley drivedevice 39. Such a pulley drive device 39 is of known type, requiring nofurther detailed description and permits controlling the speed ofmovement of the ending strip 1 through the joining and indexing station5 of the strips 1 and 2.

[0037] The means for precise control of the speed of movement of thestrip in the joining and indexing station can also be constituted by asecondary accumulation means 6 for the ending strip 1 disposed upstreamthe joining and indexing station 5. Such a secondary accumulation means6 of the ending strip 1 (FIGS. 1, 2, 5 and 9) can be present in the formof two pairs of fixed return cylinders 40 disposed symmetricallyrelative to the median bearing crosspiece 9, below the assemblies 8 forpreparing and cutting the endings strips 1 and the new strips 2, and bytwo corresponding movable cylinders 41 guided in movement relative tothe fixed return cylinders 40 by means of slideways 42 and jacks 43.This secondary accumulation means 6 permits creating a small reserve ofstrip and delivering it thereafter at low speed and under constanttension, during the connecting operation, such that the connectingposition may be predetermined with precision.

[0038] It is also possible, according to another characteristic of theinvention, to combine the means 37 and 6 for precise control of thespeed of movement of the strip through the joining and indexing station,by arrangement of these latter immediately adjacent the joining andindexing station. Thus, the movement of the ending strip 1 is subject toa double control of its speed of movement, permitting perfectpositioning of the connecting reference marks.

[0039] Moreover, there is provided, between the strip accumulator 4 andthe joining and indexing station 5, an assembly 44 for detectingreference marks 7 of the ending strip 1, which is disposed at a distancefrom the knife 24 of the pivotable junction block 10 and from theopposed transverse grooves 9′ of the median bearing crosspiece 9corresponding to a whole number of sections between reference marks 7.Such a detection assembly 44 can preferably be constituted by a pair ofphotoelectric cells or the like.

[0040] The unrolling machine according to the present invention operatesin the following manner:

[0041] After placing a new spool 2 in replacement on the spindle whoseaxis of rotation is free, the corresponding junction block 10 is movedsuch that the transverse bearing strip 16 of the new strip 2 and thesuction means 15 will be easily accessible to the operator.

[0042] As a function of the position of the reference marks 7 on thestrip, which is to say according to where they are located on thesurface oriented toward the center of the spool, as shown in FIG. 6, ortoward the exterior of the spool (FIG. 7), the return roller 26 will bemoved relative to the gripping roller 27 by the necessary distance, asexplained above.

[0043] In the first case, the indexing means 28, for example in the formof a magnifying lens, for the indexing device 11 of the new strip 2, isdisposed between the return roller 26 and the gripping roller 27. Theoperator can then, by looking through the magnifying glass constitutingthe indexing means 28 and by turning the gripping roller 27, advance thestrip 2 until the reference mark 7 coincides perfectly with an index ofsaid magnifying lens 28. In this position, there is a whole number ofsections between reference marks 7 between the magnifying glass 28 andthe position of the cut, with which exactly and perfectly coincides areference mark 7. Thus the strip 2 of the new spool is perfectlyindexed.

[0044] After the indexing operation, the strip 2 is immobilized againstthe bearing transverse strip 16 of the junction block 10 by actuatingsuction means 15. The strip 2 is then cut with the help of the knife 22and the end of the cut strip is withdrawn. Then a strip of double faceadhesive is stuck to the end of the strip 2.

[0045] The junction block 10 is then moved into the connection position,as shown in FIG. 2 at the right, and the strip 2 is tensioned byrotating the spool in the reverse direction to the normal unrollingdirection so as to obtain optimum tension in the strip, then the stripis immobilized in known manner on its spindle. As a modification, it isalso possible to control the tension of the strip with the help of atension detector or by subjection to the drive of said spindle.

[0046] When the reference marks 7 are turned outwardly of the spool itis not necessary to move the return roller 26 relative to the format ofthe sections between the reference marks 7. The strip 2 is threaded inthe same manner as when the reference marks 7 are turned toward thecenter of the spool and the indexing means 28 of the index device 11 ofthe new strip 2 is placed such that it will be at the level of the means12 for preparatory cutting of the new strip 2 (see FIG. 7). The movementof the strip 2 is effected in a manner identical to that describedabove. The same is true as to the other successive operations.

[0047] The connection cycle is explained more particularly with respectto FIGS. 9 and 10. Thus, in fifteen regions Z1 to Z15, there is given:

[0048] VA=linear speed of movement of the ending strip 1 of the firstspool, upstream of the secondary accumulation means 6

[0049] VB=linear speed of unwinding of the new strip 2 from the secondspool, upstream of the secondary accumulation means 6

[0050] VC=linear velocity of the strip, downstream of the joining andindexing station.

[0051] In the region Z1, the spool A unrolls with a speed VA=V2=nominalspeed of operation=speed of the machine to be supplied and the tractionassembly 37 for the ending strip 1 also turns at the speed VC=V2. Thestrip accumulator 4 is in working position, which is to say almostclosed and the means 37 and/or 6 for precise control of the speed ofmovement of the strip are in the rest condition. The new spool isinstalled and the end of the strip B is prepared.

[0052] In the region Z2, there is detected the next end of the firstspool A, whilst the strip accumulator 4 is in the position of FIGS. 9aor 9 b.

[0053] In the region Z3, the strip accumulator 4 is filled by spacing,in known manner, the deflecting bars from each other by means of a jack.Simultaneously, the connection cycle is triggered by acceleration of thespeed VC, then VA follows VC up to VS.

[0054] In the region Z4, VC and VA are held constant at speed V5 and thestrip accumulator 4 is full.

[0055] In the region Z5, the strip accumulator 4 being empty, VC and VAare reduced to V2.

[0056] In the region Z6 the means 37 and/or 6 for precise control of thespeed of movement of the strip are actuated. VC remains constant and VAincreases to V3.

[0057] In region Z7, after actuation of the means 37 and/or 6 forprecise control of the speed of movement of the strip, VA returns tospeed V2.

[0058] In region Z8, VC is braked until it stops, VA follows and theending strip 1 is stopped. The corresponding spool is blocked againstrotation. Strip accumulator 4 progressively empties by supplying thedownstream machine at nominal speed V2.

[0059] In region Z9, VC is slightly accelerated up to V1, which is avery low speed, the ending strip moves at a very low speed, under theeffect of the operation of means 37 and/or 6 for precise control of thespeed of movement of the strip and the reference marks 7 are sought onthe strip 1 by the detection assembly 44. When the reference mark 7 ofthe strip 1 coincides with the photoelectric cells or the like of theassembly 44, VC stops. In this position, the reference mark 7 of thestrip 1 coincides with the reference mark 7 of the new strip 2, whichwas previously indexed in region Z1. Thus, to guarantee high precisionconnection, it is necessary to move the strip 1 at a low speed and underconstant tension. This is obtained by the means 37 and/or 6 for precisecontrol of the speed of movement of the strip, operated independently orin combination, which permit delivering the strip 1 at low speed andunder constant tension.

[0060] In region Z10, VC=VA=VB=0, the strips are stopped and theirrespective reference marks 7 are in perfect correspondence. The strip 1is cut with the knife 24 and the anvil 9 and simultaneously the end ofthe strip 2 is glued to the end of the strip 1, in superposition, sashown in FIG. 8.

[0061] In the region Z11, the new spool is freed for rotation. VC isaccelerated up to V2 and VD follows.

[0062] In region Z12, VB=VC=the nominal speed of operation.

[0063] In region Z13, the position of the strip accumulator 4 isdetected (see FIGS. 9a, b, c). If the latter is too closed, it is openedmore by simultaneously accelerating VC to reach the working position ofthe accumulator; conversely, if it is too open, it is closed andsimultaneously VC is slowed.

[0064] In the region Z14 the ending spool is withdrawn.

[0065] In the region Z15, the new spool unrolls to replace the endingspool; the cycle can recommence as in region Z1.

[0066] Thanks to the invention, it is possible to provide an unrollingmachine permitting unrolling two spools and their superposed connectionwith perfect indexing of the new strip relative to the ending strip.

[0067] Of course, the invention is not limited to the embodimentdescribed and shown in the accompanying drawings. Modifications remainpossible, particularly as to the construction of the various elements orby substitution of technical equivalents, without thereby departing fromthe scope of protection of the invention.

1. Precision connection device for a continuous unrolling machine,comprising at least one means (3) for unrolling two spools, a stripaccumulator (4) and a device for connecting an ending strip (1) and anew strip (2), characterized in that the connection device isessentially constituted by adjoining an indexing station for the strips(1 and 2) and by at least one means (6, 37) for precise control of thespeed of movement of the strip through the joining and indexing station(5).
 2. Device according to claim 1, characterized in that the joiningand indexing station (5) for the strips (1 and 2) is constituted by twosymmetrical assemblies (8) for preparing and cutting the ending strip(1) and the new strip (2) and by a median bearing crosspiece (9) forcutting the ending strip (1).
 3. Device according to claim 2,characterized in that each assembly (8) for preparing and cutting theending strip (1) and new strip (2) is constituted by a junction block(10) pivotable between a preparatory position and a connecting position,by an indexing device (11) for the new strip (2) and by means (12) forpreparatory cutting of said new strip (2).
 4. Device according to claim3, characterized in that each pivotable junction block (10) is in theform of a casing which, on the one hand, is connected to a pivotinglever (13) actuated by a jack (14) articulated by its cylinder on thebody of the machine and, on the other hand, is provided with suctionmeans (15) and with a transverse bearing strip (16) for the new strip(2) during preparatory cutting and for application of an adhesive stripon the end, after said cutting.
 5. Device according to claim 4,characterized in that each pivotable junction block (10) is providedwith a knife (24) for cutting the ending strip (1), guided in a slot(25) and driven by a jack.
 6. Device according to claim 4, characterizedin that each pivotable junction block (10) is mounted on the body of themachine for movement by means of a sliding bearing actuated by a jackfor movement in direction of the median bearing crosspiece (9). 7.Device according to claim 4, characterized in that the suction means(15) consist in holes provided in a surface adjacent to the transversebearing strip (16) of the new strip (2), these holes being arranged ingroups symmetrical relative to the longitudinal axis of the new strip(2) with suction chambers controlled pairwise.
 8. Device according toclaim 3, characterized in that the preparatory cutting means (12) forthe new strip (2) is constituted by a transverse support (17), mountedwith the possibility of retractable pivoting in bearings (18 and 19) onthe body of the machine and having a guide glideway (20) for a slider(21) bearing a knife (22) loaded by a spring (23).
 9. Device accordingto claim 3, characterized in that the cutting means (12) is provided, atthe free end of the transverse support (17), with a hook or the like forholding it in retracted position.
 10. Device according to claim 3,characterized in that the device (11) for indexing the new strip (2) isin the form of a return roller (26) and a gripping roller (27), adaptedto exert traction on the new strip (2), and by an indexing means (28),such as a magnifying glass or the like, mounted movably transversely tothe strip (2) on a support (29) removably fixed in a bearing (19) of thebody of the machine.
 11. Device according to any one of claims 1 and 10,characterized in that the body of the unrolling machine is providedrespectively at each device (11) for indexing the new strip (2) and inline with the transverse bearing strip (16) of the new strip (2), in thecutting position of this strip (2), with bearings (18 and 19) formounting the transverse support (17) constituting the preparatorycutting means (12) for the new strip (2) and of the indexing means (28).12. Device according to claim 10, characterized in that the returnroller (26) is mounted in a sliding bearing (30) of the body of themachine and is movable in the direction or opposite direction of thecorresponding gripping roller (27) by means of a mechanical orelectrical control, such as a jack, a motor reducer assembly or thelike.
 13. Device according to claim 2, characterized in that the medianbearing crosspiece (9) for cutting the ending strip (1) is present inthe form of an anvil disposed between the pivotable junction blocks (10)of each assembly (8) for preparation and cutting of the ending strips(1) and new strips (2) and is provided with two opposite transversegrooves (9′) adapted to coact with the knife (24) of each pivotablejunction block (10).
 14. Device according to claim 3, characterized inthat each assembly (8) for preparation and cutting of the ending strips(1) and new strips (2) is completed by a punching device (31), mountedon the body of the machine perpendicular to the anvil forming the medianbearing crosspiece (9) and coacting with a matrix (32) provided on saidanvil.
 15. Device according to claim 14, characterized in that thepunching device (31) is constituted by a punch properly so-calledmounted at the end of a piston rod (33), in a guide chamber (34) andprovided with means (35) for application of the device against the anvilduring the punching operation.
 16. Device according to claim 15,characterized in that the means (35) for application of the deviceagainst the anvil is constituted by a sleeve movable by the control jackof the punch and provided with a resilient means (36) for compensatingthe final displacement of the punch, in the form of a spring or thelike.
 17. Device according to claim 1, characterized in that the precisecontrol means for the speed of movement of the strip through the joiningand indexing station is constituted by a traction assembly (37) for theending strip (1) of variable speed, provided between the stripaccumulator (4) and the connecting device.
 18. Device according to claim17, characterized in that the traction assembly (37) of the ending strip(1) of variable speed is constituted by a return cylinder (38), overwhich passes the strip (1), which is pressed against this cylinder (38)by means of a pulley drive device (39).
 19. Device according to claim 1,characterized in that a precise control means for the speed of movementof the strip through the joining and indexing station is constituted bya secondary accumulation means (6) for the ending strip (1) disposedupstream of the joining and indexing station (5).
 20. Device accordingto claim 19, characterized in that the secondary accumulation means (6)for the ending strip (1) disposed upstream of the joining and indexingstation (5) is present in the form of two pairs of fixed returncylinders (40) disposed symmetrically relative to the median bearingcrosspiece (9), below the assemblies (8) for preparation and cutting theending strips (1) and new strips (2), and two corresponding movablecylinders (41) guided in movement relative to the fixed return cylinders(40) by means of slideways (42) and jacks (43).
 21. Device according toany one of claims 1, 17 and 19, characterized in that the means (37 and6) for precise control of the speed of movement of the strip through thejoining and indexing station are combined by arrangement of these latterimmediately adjacent said joining and indexing station.
 22. Deviceaccording to any one of claims 1 to 5, characterized in that between thestrip accumulator (4) and the joining and indexing station (5) isprovided an assembly (44) for detecting reference marks (7) on theending strip (1), which is disposed at a distance from the knife (24) ofthe pivotable junction block (10) and transverse opposed grooves (9′) ofthe median bearing crosspiece (9) corresponding to a whole number ofsections between reference marks (7).
 23. Device according to claim 22,characterized in that the detection assembly (44) is constituted by apair of photoelectric cells or the like.